As its name suggests, a conventional switched-capacitor DC-DC converter converts a received DC input voltage into a DC output voltage.
In one conventional application of such technology, the input voltage to the conventional switched-capacitor converter falls in a range between 40 VDC to 60 VDC. In such an instance, switches in the switched-capacitor converter are controlled to transfer charge stored in capacitors, resulting in conversion of the input voltage such as a 48 VDC to an output voltage such as 12 VDC for a so-called 4:1 switched-capacitor converter. In other words, a conventional switched-capacitor converter can be configured to convert a 48 VDC voltage into a 12 VDC voltage.
To avoid so-called hard switching in the switched-capacitor converter, the switches in the switched-capacitor converter are preferably switched when there is near zero voltage across them and near zero current flowing through them.
The undesirable hard switching in a conventional switched-capacitor converter may be mitigated by placing an individual inductor in series with a respective capacitor in each stage of the switched-capacitor converter. This results in a resonant (or semi-resonant) switching converter. Such a switched-capacitor converter is sometimes termed a switched tank converter (STC). The resonant tank circuit formed by a series connection of an inductor and capacitor has an associated resonant frequency that is based upon the inductance and capacitance of these components.
Switching of the switches in the conventional switched-capacitor converter at the respective resonant frequency results in so-called zero current switching (ZCS), which reduces switching losses and provides reasonably good power conversion efficiency.